Bolt-anchor.



No. 805,040. 0 I PATENTBD NOV. 21, 1905. 0. 0. TOMKINSON.

BOLT ANCHOR.

APPLICATION FIL'ED JUNE 12-, 1905.

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Specification of Letters Patent.

Patented NOV. 21, 1905.

Application filed June 12,1905. Seria1N0. 264,749.

To ctZZ whom it may concern:

Be it known that 1, CHARLES C. TOMKINSON, a citizen of the United States, and a resident of Plainiield, county of Union, and State of New Jersey, have invented certain new and useful Improvements in Bolt-Anchors, of

which the following is a specification.

My invention relates to bolt-anchors which as usually made are composed of a plurality of seetions,.two or more, provided with an exteriorly-roughened surface for engaging a hole drilled in a wall or slab, and with an interior surface having corrugations for engagement with the thread of a bolt or screw.

My invention consists in substituting for the corrugations running spirally from side to side of the bolt-anchor section a plurality of discontinuous projections or spurs which are of practically equal efliciency in engaging the thread of the bolt and which permit the use of bolts having difierent numbers of threads to the inch.

In the drawings, Figures 1, 2, and 3 are respectively interior, exterior, and end elevations of a bolt-anchor section embodying my invention. Figs. 4:, 5, and 6 are similar views of a modified form of the device. Figs. 7, 8, and 9 are similar views of a still further modification.

l designates a bolt-anchor section shown as semicylindric, so that two such sections would make a complete tubular bolt-anchor. As shown, the section may be made of cast metal, the wall gradually increasing in thickness from its front end 11 to its rear end 12. It is provided on its exterior surface with a line of projections 13 and mid way of these is shown as having a line of star-shaped projections 14:. It is evident that these projections 18 and 14. are adapted to engage with the sides of the wall of the hole in which the anchor is inserted and that the anchor is exteriorly of substantially cylindric form.

The anchor is provided on its interior surface with a plurality of projections or spurs 15, shown as having rectangular bases and as pointed at their tips. In the example of my invention illustrated these are arranged in spiral lines, corresponding approximately at least to the pitch of a bolt-thread, and are in adjacent lines staggered with relation to each other. In the form of construction shown these projections 15 are arranged in groups, leaving a space 16 between them in which there are no projections. This form of the device will be found especially useful in that it permits the engagement of the anchor composed of the two sections 1, as described, with bolts having threads of considerable variation. It is obvious that the sections 1, instead of being semicylindric in form, may be so made that it requires three or more of them to form the complete tubular anchor. I have shown two of the projections 13 as provided with lateral extensions 17, adapted to engage with like recesses in the corresponding section, so that longitudinal displacement of the sections when they are placed in the hole is prevented. This is a well-known feature of bolt-anchors and forms no part of the present invention. By reason of the tapered thickness of the walls of the bolt-anchor the tips of the interior projections would be approximately tangential to a cone-frustum, so that the bolt-anchor will tend to be expanded to the greatest extent at its rear end by the screwing home of the bolt.

In the modified form shown in Figs. 1, 5, and 6 of the drawings the projections 15 are not divided into groups separated by plain spaces as above. This form of my device is particularly adapted to anchor-sections made of soft metal which are adapted to be considerably deformed when they are put into use.

Figs. 7, 8, and 9 represent a form of my device such as would be made from sheet metal of substantially equal thickness throughout its length and breadth. In this case the taper is provided by making the projections 18 of progressively increasing height from the front end 11 to the rear end 12 of the anchorsection. In this form the projections 18 shown on the inner face of the anchor-section are naturally depressions on the outer. surface. To assist in maintaining the anchor in its position in a wall or slab, I have shown, in addition to the corrugations 18, exterior projections 19, which of course show as depressions on the inner surface of the section.

I have illustrated several forms of my device to show that it is notlimited in construction except in being provided with discontinuous projections as opposed to the continuous lines used in former well-known bolt-anchors.

I have spoken of the bolt-anchors as usually made of aplurality ofsections. Itis of course understood that these sections may be united at certain points, it being only necessary that they be so far separated from each other as to be expansible when the bolt is screwed home. This connection of the sections may be at any desired point or points of their length. It is therefore clear that by the phrase bolt-anchor section as used in the claims I intend to include a bolt-anchor composed of any desired number of parts so far separated as is necessary to permit their expansion.

Without enumerating equivalents or specifying materials. What I claim is 1. A bolt-anchor section provided on its interior surface With a plurality of spurs arranged in spiral lines approximately corresponding to the pitch of a'bolt-thread.

2. A bolt-anchor section provided on its interior surface with a plurality of spurs located in staggered arrangement in spiral lines approximately corresponding to the pitch of a bolt-thread.

3. A bolt-anchor section provided on its interior surface with a plurality of separated groups of spurs for engaging a bolt-thread.

4. A bolt-anchor provided on its interior surface with a plurality of spurs arranged in spiral lines approximately corresponding to the pitch of a bolt-thread, the tips of said spurs being approximately tangential to a cone-frustum.

5. Abolt-anchor section formed from metal of approximately equal thickness throughout and provided With a plurality of spurs for engaginga bolt-thread, said spurs being of progressively greater height from front to rear of the section.

CHARLES C. TOMKIN SON Witnesses:

J. D. FLAoK, A. E. GALVIN. 

